With wake-up message from Capt. Kirk, space shuttle undocks for last time

After receiving a wake-up message from Star Trek's William Shatner Monday morning, the crew of NASA's space shuttle Discovery undocked from the International Space Station and began its final voyage back to Earth.

Discovery, which will be retired after returning from its 39th mission, fired its jets at 8:37 a.m. EST to separate from the space station for the final time, setting it on a course for its return to the Kennedy Space Center in Florida at 11:58 a.m. Wednesday. The shuttle's final mission included delivering supplies, spare parts, experiments and a humanoid robot to the international orbiter.

The day got off to an engaging start when Shatner, who played Capt. James T. Kirk on the original Star Trek television series and in several movies, recorded a message for the wake-up call to the members of the Discovery crew on their eighth day docked to the space station.

As the familiar theme music from Star Trek played, Shatner replaced the usual introduction for the TV series with a voice-over, saying, "Space, the final frontier. These have been the voyages of the space shuttle Discovery. Her 30-year mission: To seek out new science. To build new outposts. To bring nations together on the final frontier. To boldly go, and do, what no spacecraft has done before."

Discovery first launched into space in August 1984. It was the shuttle that returned the U.S. to space flight after the Challenger and Columbia shuttle disasters. It also was the shuttle that carried the Hubble Space Telescope into orbit and subsequently went aloft twice so astronauts could make repairs to the telescope.

During its last mission, astronauts made two spacewalks and removed the Leonardo Permanent Multipurpose Module from the space shuttle and permanently attached it to the outside of the space station. The module is a pressurized container used on shuttle missions to haul cargo to the space station and refuse back to Earth.

However, with the shuttle fleet close to retiring, this time the module became a permanent fixture on the space station, giving astronauts living there more storage room.

And as the module was attached, the humanoid robot, named Robonaut 2, officially reached its permanent home aboard the space station. The robot had traveled into space inside the module.